The present invention relates to a cable chain and more particularly to a plastic cable chain. The invention also relates to a method of manufacturing a length of cable chain and to a method of coupling the ends of the chain to make the chain continuous.
The use of plastic cable chain as a "silent drive" for office machines, such as duplicators or copiers, is well known. The main problem encountered in the use of plastic cable chain with such machines is its high incidence of failure due to breakage. The breakages occur at the weakest point of the chain which is that part at which, during manufacture, the exposed cable ends of the chain have been coupled together to make the chain continuous. One manufacturing method is to weld the free ends of the metal cable together but, although a wide variety of welding techniques have been tried, they have been found to introduce weaknesses in the welded metal leading to brittle and fatigue failures during use.
An alternative technique that has been employed is to crimp a steel bush 2 over the exposed metal ends 14, 16 of the cables as shown in FIG. 1. This method has the added advantage that the forming of the chain into a continuous length can be performed in situ thereby reducing manufacturing costs. This method however has been found to have disadvantages in that the service engineer requires special hand tools and must be extremely careful in using these tools to avoid weakening the cable. The first step involves the service engineer cutting the plastic jacket 18 (one pitch each side) lightly with a sharp razor blade all around and carefully stripping or twisting off the jacket 18 to expose the ends 14, 16 of the stainless steel cables. Extreme care must be taken at this stage to ensure no cutting or fraying of the cables which can be of very small diameter, 1 mm or less. The service engineer must then carefully slide the stripped cable into the oval splice bushing 2 having a chamfered end. Again the service engineer must take extreme care not to fray the cable and must also ensure that he feeds the cable into the chamfered end last. The bushing 2 must then be accurately centered ensuring that the chain is straight before a crimp tool is positioned over the bushing 2 and squeezed tightly for maximum splice strength. It has also been found that the failure rate of plastic cable chains having their ends crimped in this manner is undersirably high. There is a need therefore to find a means of facilitating the task of the service engineer whilst also providing a design of cable chain with a longer operational life. It is an object of the present invention to meet that need.
U.K. Patent No. 703,751 to British Ropes, Ltd. and R. Elkington, discloses belts having a plurality of belt reinforcing members embedded therein such as wire, cord, and cable extending longitudinally off the belts. In joining the ends of the belt, it is essential that the opposing ends of the reinforcing members be aligned at the meeting ends of the belt and that the reinforcing members be joined together without weakening the belt or impairing its flexibility. This is accomplished by placement of a socketed cylindrical shank having on its outer end a ring-like eyelug on each reinforcing member end. The axis of eyelug orifice is perpendicular to the axis of the shanks. The ends of the reinforcing members are inserted into the shank socket and swaged thereto. The eyelugs of each reinforcing member on opposite ends of the belt are interdigitated, so that their orifices are coaxial, thereby permitting the insertion of a flexible hinge pin therethrough, the opposite ends of which are screw-threaded and fitted with washers and retaining nuts.
U.S. Pat. No. 3,847,031 to Araya discloses a connecting link for a roller chain that includes a pair of link plates, one of the plates having integrally secured thereto a pair of connecting pins, so that the pins are cantilevered therefrom. The other link plate is installed over the distal ends of the connecting pins and a resilient locking member is placed on the distal ends of the connecting pins outwardly of the link plate.
U.S. Pat. No. 4,060,006 to Abel et al. discloses a plastic ladder chain made continuous by affixing the exposed metallic cable ends to a master coupling link of stainless steel. The cable ends of the confronting ladder chain ends are fastened to a respective one of two identical, separate links and then the separate links are connected together by a master cross link having apertures therein to receive the outer ends of the separate links. Retainer clips hold the master cross links in place by engaging annular grooves on the opposite ends of the master cross links.